Boiling paint apparatus used by Ramsay and Young, relating to Sir William Ramsay's early researches

This apparatus was developed in 1883 by Ramsay and Young to show that solids have definite ‘volatilization points’ (that is the condition of a solid analogous to that of a liquid when it is said to be boiling, or the maximum temperature which the solid at a given pressure can attain).

The left-hand vessel contains a thermometer surrounded by cotton wool, on which a block of ice was formed. The right-hand vessel was placed in a freezing mixture and the apparatus sealed after evacuation. The right-hand thermometer determined the pressure in the vessel and the temperature of the ice was measured, enabling a plot of the ice-steam system to be drawn.